Patent GB-1368400-A (GB)
Title: Bleaching process and compositions therefor
IPC: C11D3/39
Filed: 1972-08-01
Abstract: 1368400 Bleaching compositions PROCTER & GAMBLE CO 1 Aug 1972 [5 Aug 1971 29 Feb 1972 (2)] 35878/72 Heading D1P A bleaching composition comprises (a) 0.8% to 75% by weight of a water-soluble monopersulphate, a water-soluble perphosphate or an organic peracid that contains a chain of 1 to 16 methylene groups or an arylene chain comprising 6 to 8 carbon atoms, said chain terminating in a hydrogen, alkyl, aryl halogen or a group which is anionic in aqueous solution, e.g. sulphonyl, carboxyl and percarboxyl, or a water-soluble salt of said organic peracid, (b) 0.01% to 75% of an aldehyde, ketone or a precursor which yields an aldehyde or ketone in solution, said compound being an activator for peroxide oxidation with a catalytic constant, measured under prescribed conditions of at least 0.25 times that of acetone, and (c) 1% to 85% of a buffer for maintaining an aqueous solution of the composition at pH of 7 to 12. The composition may be used to remove stains from fabrics or from hard surfaces, e.g. porcelane, or to supress dye transfer when coloured and white fabrics are laundered together. Woven and knitted fabrics of cotton, wool, silk, polyester, polyamide, polyacrylic or cellulose acetate and polyester continuous filament are treated. Lists of suitable aldehyde and ketone activators are given. Buffers include sodium carbonate, sodium bicarbonate, disodium hydrogen phosphate and sodium dihydrogenphosphate. The percompound may be sodium, potassium or tetraalkylammonium monopersulphate or perphosphate (including peroxydiphosphate), and diperazelaic acid, diperadipic acid, monoperoxyphthalic and diperoxyisophthalic acid, diperoxyterephthalic acid, 4- chlorodiperoxyphthalic acid, m-chloroperoxybenzoic acid, p-nitroperoxybenzoic acid, and sodium and potassium salts thereof. Direct bleaching of stains on fabrics is carried out at 120F by aqueous solutions of the bleaching composition providing 10 to 100 ppm of available oxygen and 250 to 1000 ppm of activator. Preferably 50 to 1000 ppm of chloride or bromide salts are also present, preferably as 4% to 40% of the bleach composition. Some halide is converted to hypohalide by the percompound and acts as a bleach. Hard surface bleaching solutions contain 100 to 2000 ppm oxygen, 100 to 2000 ppm activator and 1000 to 50,000 ppm of halide ion. Dye transfer inhibition solutions contain a detergent; 25 to 50 ppm oxygen, 0.1 to 500 ppm activator and may be used to wash fabrics at 105C. Polyvinyl pyrrolidone, copolymers thereof with acrylonitrile or maleic anhydride or poly-4-vinyl-methylpyridinium iodide assist dye transfer inhibition and may be present in the solid bleach composition by 5 to 40% by weight. An anionic, nonionic or zwitterionic surfactant (lists are given) may comprise 2% to 30% by weight of the composition. The composition may also contain 10 to 60% by weight of alkali metal carbonate, bicarbonate, borate, phosphate, polyphosphate, silicate or sulphate; as an alkaline detergency builder salt. Organic builder salts are also listed. An enzyme (nature unspecified) may assist in the laundering process.